Apparatus for controlling the supply of gas to instant water heaters in circulation heating systems

ABSTRACT

A pump circulates hot water in a system including a gas fired heater and a radiator. A bypass is across the radiator and includes a heat exchanger for heating domestic water. A flow control in the system opens the bypass and shuts off flow to the radiator when domestic water is drawn. A gas rate of flow control provides full gas supply when the radiator is cut off and reduced gas supply when water flows through the radiator. The motor for the blower for removing gaseous products of combustion is at relatively high speed when there is full gas supply and at a comparatively lower speed when there is reduced gas supply.

United States Patent Inventor Georg Ilein Remscheid, Germany Appl. No. 871,937 Filed Oct. 28, 1969 Patented Aug. 24, 197] Assignee Joli. Vaillant KG Remscheid, Germany Priority Nov. 26, 1968 Germany P l8 10 900.7

APPARATUS FOR CONTROLLING THE SUPPLY OF GAS TO INSTANT WATER HEATERS IN CIRCULATION HEATING SYSTEMS 1 Claim, 2 Drawing Figs.

US. Cl.

Int. Cl. Field of Search Primary ExaminerEdward J. Michael Attorney-Darbo, Robertson & Vandenburgh ABSTRACT: A pump circulates hot water in a system including a gas fired heater and a radiator. A bypass is across the radiator and includes a heat exchanger for heating domestic water. A flow control in the system opens the bypass and shuts off flow to the radiator when domestic water is drawn. A gas rate of flow control provides full gas supply when the radiator is cut off and reduced gas supply when water flows through the radiator. The motor for the blower for removing gaseous products of combustion is at relatively high speed when there is full gas supply and at a comparatively lower speed when there is reduced gas supply.

PATENTED Aus24|91| 3.601.310

'Fig] IN V EN TOR:

APPARATUS FOR CONTROLLING THE SUPPLY OF GAS TO INSTANT WATER HEATERS IN CIRCULATION HEATING SYSTEMS BACKGROUND AND SUMMARY OF THE INVENTION This invention relates to apparatus for controlling the supply of gas to gas-heated instant water heaters which serve as heat source for a hot water circulation heating system and is an improvement in or modification of the apparatus claimed in U.S. Pat. application Ser. No. 687,267, filed Dec. 1, 1967, now U.S. Pat. No. 349,0693.

Said patent discloses apparatus for controlling the supply of gas to a gas-heated instantaneous water heater which serves as a heat source for a circulation hot water heating system in which a bypass line, controlled by a changeover valve and bypassing the radiator portion of the system, is provided between the feed and return line. The apparatus has a water actuator which responds to the flow in the bypassed portion of the system and which moves a valve to reduce the supply of gas when the bypass line is closed or throttled. A heat exchanger for heating service water may be associated with the bypass line. Throttling of the gas supply takes place during normal heating operation, i.e. when there is a flow of water in the radiator portion of the system. The arrangement set forth in the said patent makes it possible to operate at full power while service water is drawn off and during the period when the system is being brought up to operating temperature.

The exhaust gases from gas-heated continuous-flow heaters can, of course, be discharged to the open air through an exhaust-gas blower. The capacities of these blowers are selected according to the volume of exhaust gases produced when the continuous-flow heater is running under its full load for the particular installation.

According to the invention, in apparatus as set forth in said patent, a conventional exhaust-gas blower can be switched to two speeds, the higher speed corresponding to the full load for the continuous-flow heater and the lower speed to the volume of exhaust-gas occurring when the gas supply is reduced, the exhaust-gas blower being switched over by means of an electrical switch operable by the said water actuator.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic view of water heating apparatus incorporating the present invention; and

FIG. 1a shows a detail of the apparatus.

DESCRIPTION OF SPECIFIC EMBODIMENT The following disclosure is offered for public dissemination in return for the grant of a patent. Although it is detailed to ensure adequacy and aid understanding, this is not intended to prejudice that purpose of a patent which is to cover each new inventive concept therein no matter how others may later disguise it by variations in form or additions or further improvements. The claims at the end hereof are intended as the chief aid toward this purpose, as it is these that meet the requirement of pointing out the parts, improvements, or combinations in which the inventive concepts are found.

A gas burner l is supplied with gas from a pipe 2 through an on-off gas valve 3. The burner l is mounted in conventional fashion below a heating compartment (not shown) in which there is a finned block 4 acting as a heat exchanger. A return pipe or conduit 5 forming part of a circulation heating system is connected to the upstream side of the finned block 4, and a supply pipe or conduit 6 is connected to the downstream side. The return pipe 5 has a circulating pump 7 therein. The supply pipe 6 leads to a changeover valve 8 to which a bypass 9 is coupled. This bypass 9 connects the supply pipe 6 directly to the return pipe 5 and includes a heat exchanger 10 for service water. The service water flows through a coil 10 inside the heat exchanger 10. A branch pipe or conduit 6 of the supply pipe 6 leads from the changeover valve 8 to room radiators,

which are indicated at 11 and to which the return pipe or conduit 5 is also connected. When the changeover valve 8 is in the position shown, the supply pipe 6 communicates with the bypass 9, so that the circulating pump 7 sends water through a relatively smaller circuit, by way of the finned block 4, supply pipe 6, changeover valve 8 and bypass 9. The heating circuit, containing the radiators 11 and the supply-pipe branch 6', is therefore short-circuited.

The changeover valve 8 contains a valve member 8, which can be moved axially by means of a motor 12 and also forms a thermostat element. A changeover valve 8 of this type is described in more detail in British Pat. Specification No. 1,157,134. As long as service water is drawn off from the coil 10', the changeover valve 8 remains in the position shown. As soon as the drawing of service water ceases, the valve member 8' is shifted to the right by the motor 12, but it does not close the mouth 9 of the connecting pipe 9 until the supply water in the supply pipe 6 exceeds a given temperature. During the heating-up period, therefore, the changeover valve 8 occupies a position such that the supply pipe 6 communicates with both its branch 6' and the bypass 9. To achieve this operation, motor 12 is controlled by a switching device 12a actuated by the flow, or absence of flow, of water in coil 10'.

When the supply water is cold, therefore, a large volume of water flows along the connecting pipe 9 (due to the lower flow resistance) and only a small volume along the branch 6' to the radiators 11. As the supply water temperature increases, there is an increase in the proportion of water flowing through the branch 6' and a decrease in the proportion of water flowing through the connecting pipe 9, until the connecting pipe 9 is completely closed and all the water flows along the branch 6 into the heating circuit.

The branch pipe 5' includes a venturi tube 13', at which a dynamic pressure difference, dependent on the throughput, is derived in a known manner and passed to a water actuator 14' through connections .1: and y which extend between the two.

The gas valve 3, which is biased by a spring 22, rests on an annular valve seat 23. The valve 3 can be lifted off this seat by the armature of an electromagnet 25 which is provided with a dash pot device 24. The electromagnet 25 is energized by way of contacts 26 closed by a diaphragm-type water actuator 27, which is connected to a venturi tube 28 incorporated in the supply pipe 6. As long as the circulating pump 7 is running, differential pressure is produced in the venturi tube 28 and causes the water actuator 27 to respond and the electromagnet 25 to be energized. By means of this arrangement, which forms a safety device to prevent lack of water, the gas valve 3 is kept open during operation of the circulating pump 7.

A valve for regulating the amount of flow of gas is provided upstream of the valve 3. This valve comprises a disc 29 rotatably mounted below an annular valve seat 23. The disc is held by a collar 30 on this seat. It is urged toward the open position by a spring 40. The disc 29 has four sectors 29, which shroud corresponding sector-shaped apertures 23' in the annular valve seat 23 to a greater or lesser extent (FIG. la). A downwardly projecting radial lug 31 is attached to rotatable disc 29. A rod 32 engages this lug. It is actuated in the closing direction of rotation of the disc 29 by a pivoting lever 33, bearing on a rod 14" ofwater actuator 14'. This actuator, as is indicated by reference letters x, y, is connected to a venturi tube I3 disposed in a branch 5' (belonging to the radiator circuit) of the return pipe 5 Flow through the venturi tube 28 opens the gas valve 3 completely. However, as soon as hydraulic pressure is produced in the radiator circuit at the venturi tube 13 during flow through radiator 11, the disc 29 is rotated and the gas throughput is reduced.

The control pin 14" of the water actuator 14, which moves the lever 33, also operates an electrical switch 34 which is actuated and opened under a partial load, i.e. when the water actuator responds. A resistance 36 is connected in parallel with the switch 34. The switch and resistance are in series with the motor 35 of an exhaust-gas blower.

When the apparatus is operating as shown in FIG. 1, the

continuous-flow heater is in the prepare service water position. The valve 8 opens the bypass line 9. There is no flow through radiator 11 and no dynamic pressure difference at the venturi tube 13. The water actuator 14 is in its position of rest.

Due to the valve 23, 29 being fully open, the full volume of gas is fed to the burner when the gas valve 3 is opened during the preparation of service water. Under these conditions the switch 34 is closed and the resistance 36 bypassed. The exhaust-gas blower is operating at full capacity.

During heating (occurring when valve 8 opens pipe 6), the pressure difference at the venturi tube 13' in the heating circuit causes the water actuator 14' to respond. This opens switch 34 and partially closes valve 23, 29. The motor 35 of the exhaust-gas blower is then in series with the resistance 36, so that the blower runs at a lower speed.

- Iclaim:

1. In a water heater apparatus comprising a gas fired water heater, gas supply means for said heater, a radiator, first and second conduits connecting the heater and the radiator through which water circulates between the two, a pump in a conduit for causing said circulation, a changeover valve in the first conduit, a bypass connecting said valve and the second conduit and including a heat exchanger in the conduit, gas flow control means connected to one of the conduits between the radiator and the bypass for reducing the flow of gas to said heater when water is flowing through the radiator, and an electric motor for driving an exhaust gas blower, the improvement comprising:

said motor being a two-speed motor; and motor control means connected to said motor and operatively associated with said gas flow control means and connected to said gas supply means for operating said motor at a comparatively low speed when water is flowing through the radiator and at a comparatively high speed when water is not flowing through said radiator. 

1. In a water heater apparatus comprising a gas fired water heater, gas supply means for said heater, a radiator, first and second conduits connecting the heater and the radiator through which water circulates between the two, a pump in a conduit for causing said circulation, a changeover valve in the first conduit, a bypass connecting said valve and the second conduit and including a heat exchanger in the conduit, gas flow control means connected to one of the conduits between the radiator and the bypass for reducing the flow of gas to said heater when water is flowing through the radiator, and an electric motor for driving an exhaust gas blower, the improvement comprising: said motor being a two-speed motor; and motor control means connected to said motor and operatively associated with said gas flow control means and connected to said gas supply means for operating said motor at a comparatively low speed when water is flowing through the radiator and at a comparatively high speed when water is not flowing through said radiator. 